RCA TV (bar on screen)

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  #1  
Old 09-28-08, 04:29 PM
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RCA TV (bar on screen)

I am working with an RCA model 32F530T TV.
The chassis number is ATC113-CD4.
Just replaced a flyback and got the unit running
however Iím noticing a bar at the top of the screen.
The bar is not visible when you first turn the set
on. It starts to appear after the set has been on about
10-15 minuets (see screen pic below).



The bar does not seem to block or distort the images on the screen but it is present. I tried replacing the vertical output
IC with no change in operation.
I also tried freezing various areas of the vertical section
including the 56 pin processor chip which also
plays a roll in vertical output.

Any help appreciated
thanks.
 
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Old 09-28-08, 07:14 PM
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Can you still detect the bar when an image is showing?Is it only the blue that has the bar?
On this problem I would start fresh and treat it as a new unrelated problem to the first one.Start by isolating it to one or all the colors.Since you froze the vertical,then that leaves the voltage supply or the video.If it is only the blue ,I would check for differences in the blue,red and green video voltages.If it is present on all the colors ,I would check for low voltage on the crt board and work back from there.
Let me know what you find out and I'll pull the diagrams and we'll find it!
 
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Old 09-28-08, 09:32 PM
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Originally Posted by craftsman_50 View Post
Can you still detect the bar when an image is showing?:
Yes,
I only used a solid background because it makes it easier to see in the pic. The blue background comes from the VCR that Im using when its turned on but have the tape on stop. Its a little like vertical foldover except it doesnt really distort the image along
with it.

Is it only the blue that has the bar?
On this problem I would start fresh and treat it as a new unrelated problem to the first one.Start by isolating it to one or all the colors.Since you froze the vertical,then that leaves the voltage supply or the video.If it is only the blue ,I would check for differences in the blue,red and green video voltages.If it is present on all the colors ,I would check for low voltage on the crt board and work back from there.
Let me know what you find out and I'll pull the diagrams and we'll find it!:thumbup
Great, The only one I have thats even close is CTC203
While your doing that I will be checking a couple of other items.

Thanks
 
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Old 09-29-08, 05:58 AM
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Update:

I noticed when I grab the black and brown wires going to the back of the yoke (see pic below), the amount that the bar comes down the screen will change. These two wires go to the vertical section.

 
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Old 09-29-08, 06:41 PM
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Did you check to see if all the colors,red,green also had the bar?We are trying to isolate the problem to a single area of the set.
 
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Old 09-29-08, 07:21 PM
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Update:
Found a bad cap (cv26) which is .47uF cap
connected between two pins of the main 56 pin IC chip.
I froze the cap and the bar went away. Actually it looks to
be a form of vertical fold over. Anyway, I replaced it with
another cap with same value but it was a different type.
I came back later and the bar was starting to become
present again. I sprayed the cap and the picture went back
to normal (wrong type of cap I suppose). I found another
cap of the same composition as the original however the
value is smaller .22uF (only one I could find). I have it
running right now and so far so good. Although the vertical
size is just a tiny bit stretched. Some of the text and numbers
at the bottom of the screen are cut off at the very bottom,
But at least I will be able to test the unit until I get the exact
value. I will let you know how it goes.
 
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